Problem with proportional editing on a curve
If it's a Bezier curve, your proportional edit circle has to encompass the handles of the point as well as the point to move it. GL  Ten four rubber ducky.  Over and out. 

It looks like Blender calculates "connected" from the point and traces it back down the original curve, and if you connect 2 ends of the curve with F key (make segment), Blender doesn't read that as a new path, so to speak.  I'm not sure how to fix that though.  Hope this makes sense.